Questions & Answers about Svijet je lijep.
Croatian simply does not use articles (no a/an or the) as separate words.
Whether something is definite or indefinite is understood from context, word order, and extra words like ovaj (this), taj (that), onaj (that over there), etc.
So Svijet je lijep is normally understood as a general statement, the same way English would say The world is beautiful, even though there is no Croatian word corresponding to the here.
Svijet is in the nominative singular case.
Ways to see this:
- It is the subject of the sentence (the thing being talked about).
- In a simple sentence with biti (to be) like X je Y, both X and an adjective describing it are in the nominative.
- Masculine nouns in the nominative singular usually end in a consonant: svijet, grad, stol, pas.
So in Svijet je lijep, both svijet (noun) and lijep (adjective) are nominative singular.